That's the inevitability rock 'n' roll fans have frequently been reminded of in recent years. The people that make up the exclusive club of rock royalty — those who've strut and slithered and windmilled guitars for decades and sometimes seem like they'll do so forever — will someday be gone. And with them will go an era that long seemed everlasting.

This situation we've found ourselves in, one of coming to grips with the mortality of the rock-star heroes of the '60s, '70s and beyond, is at the core of the new book from Appleton native Steven Hyden. "Twilight of the Gods: A Journey to the End of Classic Rock" (Dey Street, HarperCollins Publishers), released earlier this month.

The 40-year-old Hyden is an Appleton East High School graduate who in the 1990s and early 2000s worked as a reporter for The Post-Crescent. He's since gone on to write for the A.V. Club and Grantland and now is the cultural critic at UPROXX.

Steven Hyden(Photo: Photo courtesy of Steven Hyden)

Growing up in the Fox Cities, it wasn't comic books or athletes he was fixated on. Rock stars were his superheroes — men and women (although, let's face it: mostly men) with otherworldly talents traversing the globe, conquering all — sometimes even tights and capes.

"Of course, those people weren't gods at all, but rather mortals who would grow old, make comeback records with Don Was and/or Jeff Lynne, and take money from beer companies for their overpriced, nostalgia-driven concert tours."

The book follows both the journey of its author from cassette-collecting pre-teen to a married father of two and that of the classic-rock era, which blossomed in the '60s and essentially ran its course by the end of the '90s.

"I call it an affectionate critique," Hyden said by phone earlier this month. "I have a lot of affection for the era, but I'm also critiquing it at the same time. I think that's the only responsible way to revisit some of this stuff."

We're not only in the twilight of the gods because still-standing members of bands like the Beatles, the Stones, Led Zeppelin and Pink Floyd are well into their 70s. We're also there because the sun is setting on the days of holding them up as deities.

While the tales of their decadence were once celebrated, the evolution of society hasn't worked in their favor. A group of 20-something British dudes getting loaded, trashing a hotel room and treating women like disposable toiletries doesn't hold up nearly as well as "Led Zeppelin IV" or "Sticky Fingers."

"Twilight of the Gods: A Journey to the End of Classic Rock"(Photo: Amazon)

"Twilight of the Gods" is certainly affectionate, but it's no love letter. Nobody writes to the apple of their eye re-contextualizing past actions for the #MeToo era. It's noble work, though, and allows us to see these idolized rockers more for what they are: flawed human beings (some more than others, of course) who gifted the world remarkable art.

While along the way he tackles the "Is rock dead?" question, the genre known as "dad rock" and what can be gleaned from the albums his parents leaned on post-divorce, Hyden's adventure begins as a child hooked on northeast Wisconsin radio. WIXX, WOGB and WAPL especially laid a foundation that later would support his personal and professional pursuits.

One key moment he zeroes in on is a Who concert in Chicago in 2012. While the band's two remaining original members Pete Townshend and Roger Daltrey, then in their late 60s and who a half-century earlier hoped they'd die before they got old, did their best to project immortality, Hyden couldn't help but realize they looked "really (expletive) old."

He had a realization that for years he'd pretended these mythical beings would be around forever — but they won't. From Townshend and Daltrey to Mick and Keith to Dylan and The Boss, classic-rock icons are a finite resource.

That Who show (which he writes was still incredible, by the way) gave Hyden the initial idea for "Twilight of the Gods." But it wasn't until the series of high-profile rock deaths in 2016, which included David Bowie, Prince and Glenn Frey, that he was able to sell the book to a publisher. (That, and presumably the success of his first book, "Your Favorite Band Is Killing Me: What Pop Music Rivalries Reveal About the Meaning of Life," released in May 2016.)

It was in the aftermath of those deaths that the writing began, and it wrapped up around the time music fans were mourning the loss of Tom Petty.

Some parameters he sets up to contextualize classic rock could help our understanding of it for years to come. For instance, he lays out a thorough distinction between classic rock, meaning the rock music deemed by the culture as most valuable, and classic rock, defined mostly by whether or not it's music WAPL and its ilk have ever given a push. REO Speedwagon, for instance, fits one classification but not the other.

Another is the parameters of the classic-rock era. It begins, Hyden argues, with the Beatles' "Sgt. Pepper's Lonely Hearts Club Band" in 1967 and ends with Nine Inch Nails' "The Fragile" in 1999. With "Sgt. Pepper," the Beatles established the rock album as we know it. More than 30 years later, digital downloads sent it into the void.

"When I wrote that (classic rock ends with "The Fragile") I knew that some people would probably be irritated because I think with classic rock, people have a fixed idea of what it is — even though it is a very nebulous term. But whatever definition you have in your head, that’s the right definition," he said. " ... Part of the thing in the book in talking about 'The Fragile' was talking about the end of the rock album being a certain type of cultural signifier or artifact and it seemed like once Napster came into effect in the late '90s, the internet became the hub for music fans to gather around rock music."

While Hyden's journey from a young avid WAPL listener to the elite class of contemporary music critics is littered with local connections, there's one line of text before even the table of contents that'll stand out to many Appleton readers: A dedication to the late Stan Erickson, best known as co-owner of New Frontier Record Exchange.

The Durkee Street record store closed in 2008, but during Hyden's formative days of musical exploration, Erickson exuded that rock 'n' roll essence usually restricted to MTV and the pages of Rolling Stone.

"That was the most rock 'n' roll place in Appleton, as far as I'm concerned, when I was a kid," he said. "It's weird — I can't speak to him as a man necessarily because I didn't know him that well. He was as much a myth to me as rock stars at the time. He was like a real live rock star to me."

Hyden said back in the days when he was picking up Sex Pistols and Queen cassettes at New Frontier, Appleton was a place nobody talked about on a national level. The same could even be said for the state of Wisconsin. This was his way of using his platform to recognize where he came from and the closest thing to Neil Young the place had.

"As long as this book's in print, Stan Erickson will live on in some way and that made me feel very good," he said.

Hyden's next book project is a first-person memoir from the Black Crowes drummer Steve Gorman. The southern rocker's story has "every rock 'n' roll cliche that you can imagine," Hyden said, so he's excited about what's to come. It'll likely be out in 2019.

"The Black Crowes story is so rich, and there's so much material there, and it hasn't' really ever been told in any format, so I think it's going to come off really well," he said.

He's also still hosting the "Celebration Rock" podcast, which recently crossed the 100-episode mark. The weekly show is a mix of critical discussions with other writers and musicians and straightforward interviews. Among those Hyden's talked to one-on-one: the "golden god" himself Robert Plant.